How to rotate a parabula vector around its max vale

Hello,

I am fighting this task for some days now with no solution ye, so maybe someone will be able to shade some light...

I have a 1D vector which when plotted is forming an asimmetric parabula. I would like to rotate this vector around its max value (peak), creating a 2D matrix so a bell shape will be created ( like rotating it around the Y axis)

Any ideas how to do this?

Thanks a lot!

Tomer Braier

Answer 1

[Star Strider]

I don’t know what you mean by an ‘asymmetric parabola’. I thought parabolas were by definition symmetric about some axis.

This works with a parabola symmetric about zero:

px = @(x) 5 - 3.*x.^2;          % Parabola As Function Of ‘x’
py = @(y) sqrt((5-y)./3);       % Express Parabola As Function Of ‘y’

x = linspace(0,5,50);           % Set To Avoid Complex Values, So Must Be <=5 Here
P = py(x);                      % Evaluate Parabola In ‘y’

[X,Y,Z] = cylinder(P);          % Use ‘P’ To Define Cylinder Profile

figure(1)
surf(X,Y,Z)                     % Plot Parabola

You will probably have to experiment with it to get the result you want. This is simply one way to do it.

[Tomerbr braier]

Thanks Star for your detailed answer. I'm afraid I might explained the problem in a wrong way, thought. I have a vector of numbers, 1D. It is forming a parabulic shape around its max value. I don't know the exect formula which describe the parabula. I want to be able to rotate or maybe better put, revolve, the vector around its max value to obtain 2D matrix.

Do you think I still be able to do it using "cylinder"?

Thanks in advance,

Tomer

[Star Strider]

My pleasure!

You may be able to, depending on your data. It needs to be close to symmetric about some value to do what you want. I would have to make it symmetric and use half of it.

If you have your vector in a file, upload it here (use the ‘paperclip’ or ‘staple’ icon) and I’ll do my best to make it work with cylinder.

I didn’t know if you had data or a function so I didn’t know exactly how to proceed.